Gas turbine systems of the above mentioned kind are known in prior art. During the operation, ambient air is compressed and directed towards the burner arrangement. Inside the burner arrangement the compressed air is mixed with fuel, and the created fuel-air-mixture is ignited within the combustion chamber to generate hot combustion gases, which are directed towards the turbine via the transition duct. The turbine extracts rotational energy from the hot combustion gases and drives a load, such as a generator.
With increasing operating temperatures it is often necessary to cool components of a gas turbine system in order to counteract a limitation of a useful life of the gas turbine system. In this context it is known to provide the transition duct with a cooling air channel extending axially substantially over the entire length of the transition duct and having multiple inlets and multiple outlets. As used herein the terms “axial” and “axially” refer to directions and orientations extending substantially parallel to the longitudinal axis of the transition duct. Such a cooling air channel design has the drawback that the cooling air distribution has a significant uncertainty due to the multiple inlets and outlets, which needs to be covered by additional cooling air.
However, additional cooling air negatively affects the aim to meet low NOx emissions.